1. Technical Field
Example embodiments relate generally to a memory device and more particularly to a memory module and a memory system including the memory module.
2. Description of the Related Art
Semiconductor devices widely used in high-performance electronic systems have experienced improvements in both capacity and speed. A dynamic random access memory (DRAM) is a volatile memory which stores data corresponding to charge in capacitors. The charge stored in the capacitor may leak such that the data therein may be retained for only a limited time before degradation occurs to the point where the state of the data may be unreliable. Therefore, the refresh operation is typically required in the dynamic random access memory. In general, when a particular row address of the DRAM is frequently accessed during a predetermined time period, corresponding memory cells of the particular row address may be deteriorated and need to be refreshed.